Vehicle response systems of various types are known and examples of these are disclosed in GB 2 356 960, WO 00/42562, EP 1 085 696, U.S. Pat. No. 6,070,123, U.S. Pat. No. 3,720,911 and JP 2 000209651. In such systems, a message identifying a vehicle is transmitted wirelessly to some remote point and results, for example, in a predetermined application being formed, which application is standard and is common to all enquiries from all vehicles. Such systems are therefore relatively inflexible and do not permit “tailored” responses to be performed.